A verbal is a verb that acts like a different part of speech. Infinitives, gerunds, and participles are all types of verbals. An infinitive is a verbal consisting of to + a verb, and it acts like a subject, direct object, subject complement, adjective, or adverb in a sentence.
HeadOn is the brand name of a topical product claimed to relieve headaches. It achieved widespread notoriety in 2006 as a result of a repetitive commercial, consisting only of the tagline HeadOn. Apply directly to the forehead, stated three times in succession.
Head is typically denoted in terms of length; e.g. Feet of head, meters of head, etc. What this practically means is 1 foot of (water) head is the pressure that would exist at the bottom of 1 foot of water, which is also be the same as the amount of pressure required to lift water 1 foot. It is directly proportional to the density of the fluid.